President Trump isn't content to be leader of the free world. He wants to be head of all lines, too. In yet another humiliating moment for the country, President Trump seemingly shoved Montenegro's Prime Minister Dusko Markovic while at the NATO conference in Brussels today. After pushing Markovic, the president subtly demonstrated his dominance by pulling on his jacket like the big boy he is. SEE ALSO: Here's what it would take for Trump to actually get impeached Watch our adult child president at work. Montenegro recently joined NATO, despite efforts by Russian allies in the country to block the move. A White House Advisor responded to the video by claiming that Trump's push was a "casual greeting" that he's done many times before. How comforting! WH official: Looks like Trump was slapping him on the arm as a "casual greeting," a "greeting" he's done many times before t.co/Mi0vkdg8Za — Tara Palmeri (@tarapalmeri) May 25, 2017 Trump's push followed a historically embarrassing speech at the conference where he enjoined his fellow members to contribute more of their budgets to defense. As pundits all across the political spectrum have repeatedly pointed out, that's not how NATO works, but oh well. It's not America first, it's Trump first, everyone. WATCH: Melania Trump doesn't want your pity for her 'boy-like' husband